Brake actuating assembly for motor vehicles

ABSTRACT

The assembly includes a master brake cylinder (10) to which at least one brake circuit can be connected, a modulator (12) and a pneumatic braking force booster (14). For modulating the pressure in the brake circuit the modulator (12) is connected to the master brake cylinder (10). The braking force booster (14) comprises a housing (34, 36) having at least one partition (38) movable in piston-like manner. For transmitting reaction forces of the master brake cylinder (10) to a vehicle wall (20) at least one connecting pin (16, 18) extends through the housing (34, 36) of the braking force booster (14). The modulator (12) is likewise mounted with bypassing of the master brake cylinder (10) on at least one connecting pin (16, 18) which extends through the housing (34, 36) of the braking force booster (14). This avoids vibrations generated by the modulator (12) being transmitted directly to the master brake cylinder (10) and possibly damaging the latter in the course of time.

The invention relates to a brake actuating assembly for motor vehiclescomprising

a master brake cylinder to which at least one brake circuit isconnectable,

a modulator which is connected to the master brake cylinder to modulatethe pressure in the brake circuit,

a pneumatic braking force booster which comprises a housing having atleast one partition movable in piston-like manner and

at least one connecting pin which extends through the housing of thebraking force booster for transmitting reaction forces of the masterbrake cylinder to a vehicle wall and the intermediate wall of thebraking force booster.

DE 2845794 Al discloses a braking force booster in various constructionswhich in the manner described above is combined by means of a connectingpin with a master brake cylinder to form a brake actuating assembly.Such an assembly has also already been supplemented by a modulator whichfor modulating the pressure in at least one brake circuit has beenconnected to the master brake cylinder. The modulator has also beensecured mechanically to the master brake cylinder.

DE 3611045 Al further discloses a brake actuating assembly in which ahydraulic high-pressure braking force booster and a modulator aremounted on a common flange which is configured for securing to thesplashboard of a vehicle. Mounted on an end plate of the braking forcebooster remote from said flange is a master brake cylinder having fourwheel brake cylinder connections. Secured to each of said connections isan electromagnetic valve controlled by the modulator having a screw-inthread for this purpose.

Common to both the brake actuating assemblies described above is thatthe mechanical and hydraulic connection between the master brakecylinder and at least one of the valves associated with the modulator issimple to establish and when necessary also simple to release again. Theadditional loading of the master brake cylinder by a modulator connectedthereto also appeared acceptable in brake actuating assemblies of thetype described at the beginning because the master brake cylinder is inturn secured via the connecting bolts or pins reliably to a vehicle wallwithout appreciably subjecting the braking force booster itself to aload.

In assemblies of the type corresponding to the preamble which are madein large series production however in operation in some cases damage tothe master brake cylinder has been observed which could not be explainedby the mechanical and hydraulic loads to be expected and for this reasonmaterial or machining faults were suspected. With such damage, there isfundamentally the danger that it will not be noticed for a long time andsuddenly lead to complete failure of the master brake cylinder.

The invention is based on the problem of considerably reducing, if notcompletely excluding, the danger that under certain construction,material and production conditions leakage occurs at the master brakecylinder.

This problem is solved according to the invention in a brake actuatingassembly of the type described at the beginning in that the modulator islikewise mounted with bypassing of the master brake cylinder on at leastone connecting pin which extends through the housing of the brakingforce booster.

This achieves a mechanical separation of modulator and master brakecylinder; the necessary connection lines between the two are adequatelyyieldable so that they can transmit only negligibly small mechanicalforces.

The invention is based on the recognition that the previously only veryrarely occurring damage, nevertheless very serious because of theirpossibly grave consequences, to master brake cylinders of brakeactuating assemblies according to the preamble are due to the fact thatthe modulator valves opening and closing in rapid succession when themodulator becomes active generate vibrations in a modulator connectedmechanically to said mater cylinder which can superimpose themselves onvehicle vibrations and other factors loading the master brake cylinder,in particular the hydraulic pressures obtaining therein, in such anunfavourable manner that in the cylinder wall of the master brakecylinder a crack arises which sooner or later can result in a leak.

In the brake actuating assembly according to the invention, due to themounting of the modulator separate from the master brake cylindervibrations originating from the modulator valves are not transmitted tothe master brake cylinder or are transmitted only to a greatly reducedextent. Nevertheless, a close proximity can be maintained between themaster brake cylinder and modulator as is fundamentally desired becauseof the restricted space available and in the interest of shortconnecting lines.

The invention can be configured in that the modulator and a flangecarrying the master brake cylinder are mounted on at least one commonconnecting pin which extends through the braking force booster and theflange.

In another embodiment of the invention the modulator is secured to aflange which also carries the master brake cylinder and is mounted on atleast one connecting pin which extends through the braking forcebooster.

In each case it is expedient for the modulator to be mounted via atleast one rubber spring element.

It is further advantageous for the securing of the modulator to bereleasable with continuing securing of the master brake cylinder. Thisfacilitates mounting and dismounting of the assembly.

Finally, it is advantageous for the modulator to be connected to themaster brake cylinder solely with one or several curved pliableconnecting lines. In this manner the master brake cylinder is kept freefrom every avoidable load.

Examples of embodiment of the invention will be explained in furtherdetail hereinafter with the aid of schematic drawings, wherein:

FIG. 1 shows the front view of a first brake actuating assemblyaccording to the invention,

FIG. 2 shows the axial section II--II of FIG. 1,

FIG. 3 shows the front view of a second brake actuating assemblyaccording to the invention,

FIG. 4 shows the axial section IV--IV of FIG. 3,

FIG. 5 shows the front view of a third brake actuating assemblyaccording to the invention,

FIG. 6 shows the axial section VI--VI of FIG. 5 and

FIG. 7 shows the axial section VII--VII of FIG. 5.

In all the three examples of embodiment illustrated the brake actuatingassembly includes a hydraulic master brake cylinder 10, a modulator 12,a braking force booster 14 and at least one pair of connecting pins 16and/or 18. The connecting pins 16, 18 extend parallel to the axis A ofthe braking force booster 14 through the latter and serve to secure theentire assembly to a vehicle wall 20. The master brake cylinder 10 isarranged coaxially with the braking force booster 14, partiallyincorporated into the side thereof remote from the vehicle wall 20 andmounted in usual manner by means of a flange 22 which bears on ashoulder 24 of the master brake cylinder 10.

In all the three examples illustrated the flange 22 is a plate-likecomponent made separately from the braking force booster 14, that isaccording to FIGS. 1 and 2 and FIGS. 3 and 4 a casting or forged part,according to FIGS. 5 to 7 however a part stamped from sheet metal, andis pushed onto the portion of the master brake cylinder 10 whichprojects out of the braking force booster 14 forwardly, that is to theleft in FIGS. 2, 4 and 6, and has a smaller diameter than the portion ofthe master brake cylinder 10 engaging into the braking force booster 14.The flange 22 may also be welded to or made integrally with the masterbrake cylinder 10. In every case the flange 22 is to be considered notas part of the master brake cylinder 10 but as separate component in thesense that forces loading the modulator 12 and possibly carried awayfrom the latter via the flange 22 do not also subject the master brakecylinder 10 to a load.

The modulator 12 is connected to the master brake cylinder 10 by acurved connecting line 26 which is pliable at least along a part of itslength and is thereby, unable to transmit appreciable mechanical forcesfrom the modulator 12 to the master brake cylinder 10. Formed on themodulator 12 is a sleeve-like mounting member 28 which contains a pairof rubber spring elements 30. Also secured to the modulator 12 is astirrup member 32 which forms a constructional unit with a furtherrubber spring element 30.

In all the three embodiments illustrated the braking force booster 14comprises a two-part housing 34, 36 made up of a front housing part 34and a rear housing part 36, both of plastic. The interior of the housing34, 36 is divided by a partition 38 which is movable in piston-likemanner and at which on actuation of the brake a pressure differenceobtains by which the master brake cylinder 10 is actuated in the usualmanner which does not need to be explained. As also usual, the partition38 is sealed by resilient sleeves 40 with respect to the tubularconnection pieces 42 and 44 which are formed on the front housing part34 and the rear housing part 36 respectively.

In the embodiment of a brake actuating assembly illustrated in FIGS. 1and 2 only two connecting pins 16 are provided which both connect theflange 22 as well as the modulator 12 directly to the vehicle wall 20.The lower of said two connecting pins 16 extends through the sleeve-likemounting member 28 of the modulator 12 and through the rubber springelements 30 contained therein; the upper connecting pin 16 howeverextends through the rubber spring element 30 enclosed by the stirrupmember 32. The two housing parts 34 and 36 are held directly together bynuts 46 and 48 which bear in air-tight manner on said parts and arescrewed onto the connecting pins 16 so that said parts cannot separatefrom each other even when the flange 22 has not yet been mounted. Theflange 22 is not mounted until after installation of the master brakecylinder 10 and is secured by a further pair of nuts 50 screwed onto theconnecting pins 16. The modulator 12 is secured with further nuts 52 onthe connecting pins 16.

In the embodiment illustrated in FIGS. 3 and 4 two pairs of connectingpins 16 and 18 are provided which all extend axis-parallel through thebraking force booster 14 and hold together the housing parts 34 and 36thereof by means of nuts 46 and 48. In contrast to FIGS. 1 and 2 the twoconnecting pins 16 extend past the flange 22 but as in FIGS. 1 and 2through the sleeve-like mounting member 28 or the stirrup member 32including all the associated rubber spring elements 30. The twoconnecting pins 18 extend however, identical in this respect to FIGS. 1and 2, through the flange 22 but terminate just before the latter and donot serve to mount the modulator 12.

In the embodiment according to FIGS. 5 to 7 only one pair of connectingpins 18 is provided which terminate at the front side of the flange 22and are not directly connected to the modulator 12. The modulator 12 issecured to the flange 22 by a pair of screws 54 extending through thesleeve-like mounting member 28 and the stirrup member 32 and theassociated rubber spring elements 30, said flange 22 thereby carryingboth the master brake cylinder 10 and the modulator 12.

We claim:
 1. Brake actuating assembly for motor vehicles comprisingamaster brake cylinder (10) to which at least one brake circuit isconnectable, a modulator (12) having a fluid connection with said masterbrake cylinder (10) to modulate the pressure in the brake circuit, Apneumatic braking force booster (14) which comprises a housing (34, 36)having at least one partition (38) movable in piston-like manner and atleast one connecting pin (16, 18) which passes through the housing (34,36) of the braking force booster (14) for transmitting reaction forcesof the master brake cylinder (10) to a vehicle wall (20), characterizedin that the modulator (12) is mounted out of direct contact with saidmaster brake cylinder (10) on said at least one connecting pin (16, 18)which passes through the housing (34, 36) of the braking force booster(14) and is connected to said vehicle wall.
 2. Assembly according toclaim 1, including a flange (22) carrying said master brake cylinder(10) characterized in that said modulator (12) and said flange (22) arecommonly mounted on said at least one connecting pin (16, 18) whichpasses through the braking force booster (14) and through said flange(22).
 3. Assembly according to claim 1, including a flange (22) carryingsaid master brake cylinder (10) characterized in that the modulator (12)is also secured to said flange (22) separately from said master brakecylinder (10), said flange (22) being mounted on said at least oneconnecting pin (16, 18) which passes through said braking force booster(14).
 4. Assembly according to any one of claims 1 to 3, characterizedin that said modulator (12) is mounted on said at least one pin (16)(18) by way of at least one rubber spring element (30).
 5. Assemblyaccording to any one of claims 1 to 3, characterized in that saidmodulator (12) is releasable from said at least one pin (16, 18) withoutreleasing the master brake cylinder (10).
 6. Assembly according to anyone of claims 1 to 3, characterized in that the modulator (12) isconnected to the master brake cylinder (10) only by at least one curvedpliable fluid connecting line (26).